Reading Test

Questions 1-10

Lichens, of which more than twenty thousand species have been named, are complex associations between certain fungi and certain algae. The lichen itself is not an organism; rather it is the morphological and biochemical product of the association. Neither a fungus nor an alga alone can produce a lichen.

The intimate relationship between these two living components of a lichen was once erroneously thougt to represent mutualism. In mutualism relationships, both participants benefi. With lichens, however it appears the fungus actually parasitizes the algae. This is one of the conclusions drawn from experiments in which the two components of lichens were separated and grown apart.

In nature, lichen fungi may encounter and grow around several kinds of algae. Some types of algae the fungi may kill; other types it may reject. Lichen algae are autotrophic, meaning they make their own food through photosynthesis. Lichen fungi are heterotrophic, meaning they depend upon the algae within the lichen to supply their food. Up to ninety percent of thee food made by the green algal cells is tansferred to the fungus. What, if anything, the fungus contibutes to the association is not well understood.

Lichens are hardy. They grow in many habitats and are often pioneers in hostile environments where few other organisms can flourish. They have been known to grow endolithically , having been discovered thriving inside of rocks in Antartica. Lichens help reduce erosion by stabilizing soil. Several kinds of insects glue lichens to their exoskeletons for camouflage. Many species of birds use lichens as building materials for nests. Humans have used lichens for dyes and antibiotics.

Questions 11-20

Description: The adult House Cricket is about two centimeters in length. The body is usually light brown with black markings about the head and thorax. The female is told from the male by the presence of an ovipositor, a long extension attached to the end of the abdomen, used for depositing eggs in the soil. House crickets have conspicuous jumping legs and have two pairs of wings, of which, only the back pair are used for flight.

Habitat: House Crickets can be found in a variety of habitats including woodlands, suburbs, urban areas, buildings, ducts, siding, restaurants and anywhere else there happens to be a food supply and warm air. Although many crickets die off in the colder months, those that manage to find their way indoors can stay alive year round.

Reproduction: Crickets reach sexual maturity between eight and twelve weeks after birth. Males attract mates by rubbing their wings together to produce a noise sometimes referred to as "chirping". Technically, this process is called stirdulation. Interestingly enough, the rate in which a cricket "chirps" is determined by the temperature outside. When it is warmer, crickets chirp faster. Scientists can actually tell the exact outdoor temperature by timing the rate of cricket "chirpings". After the male mates with female, the female will lay between 50 and 100 eggs in the ground or another soft surface. The eggs hatch in about two weeks.

Life Cycle: Incomplete Metamorphosis: egg -> nymph -> adult

Diet: House Crickets will eat just about anything including soft plant matter, insects, young crickets, and decomposing matter.

Questions 21-25

Rainbows are often seen when the sun comes out after or during a rainstorm. Rainbows are caused when sunlight shines through drops of water in the sky at specific angles. When white sunlight enters a raindrop, it exits the raindrop a different color. When light exits lots of different raindrops at different angles, it produces the red, orange, yellow, green, blue, indigo, and violet that you see in a rainbow. Together, these colors are known as the spectrum. These colors can sometimes be seen in waterfalls and fountains as well.

Did you know that there are double rainbows? In a double rainbow, light reflects twice inside water droplets and forms two arcs. In most double rainbows, the colors of the top arc are opposite from those in the bottom arc. In other words, the order of colors starts with purple on top and ends with the red on bottom. In addition, rainbows sometimes appear as white arcs at night. These rainbows are called moonbows and are so rare that very few people will ever see one. Moonbows are caused by moonlight (rather than sunlight) shining through drops of water.